The building industry has long used overlapping shingles in residential home construction. More specifically, the shingles are generally made from a flexible sheet of felt which has been saturated or coated with a waterproof substance such as asphalt and then covered with a weather-resistant surface of granular mineral material, such as slate or granulated rock. Such shingles are usually rectangular in shape and combined with other substantially identical shingles in an overlapping relation to thereby provide a protective cover for a sloping roof surface.
A desired characteristic of such shingle elements is that when arranged in the overlapping fashion, the exposed surfaces of the shingle element should simulate a regular pattern typical of a genuine slate covered roof. Thus, in addition to protecting the roof against the weather, the shingle elements also serve an aesthetic function. A homeowner is provided with an attractive roof having the appearance of random edges and shadow lines normally associated with authentic slate shingles but at a fraction of the cost.
The above so-called "strip shingles" generally comprise a butt portion having a generally uninterrupted exposed surface extending from a leading edge to a trailing edge thereof. The butt edge is defined by the lower edge of the butt portion and may include particular aesthetic features such as a jagged surface to simulate the wooden shakes or other repeating geometric patterns to imitate slate, tile, etc.
One example of such a shingle element is shown in U.S. Pat. Des. No. 265,510 (Bedwell, Jr.) which illustrates an asphalt strip roofing shingle provided with an irregular surface extending along the butt edge of the shingle and further including shadow lines extending vertically along the length of the shingle. Thus, when a plurality of such shingles are arranged in an overlapping fashion, the butt edge provides an overall appearance of a slate roof with the vertical shadow lines delineating the appearance of individual shingles.
Another prior art shingle of the type discussed is shown in U.S. Pat. No. 4,333,279 (Corbin et al.) which additionally provides slot cut-outs at spaced uniform intervals across the butt portion and extending vertically substantially fully across the exposed butt portion and upwardly from the butt edge thereof. These slot cut-outs define tabs which, when combined with other such shingles, simulate a regular pattern of, for example, a slate shingle roof.
U.S. Pat. Des. No. 309,027 (Noone et al.) discloses a shingle similar to the above cited Corbin et al. patent but further disclosing various shading embodiments to denote a variety of individual shingles.
U.S. Pat. No. 1,911,014 (Cowan) discloses a siding shingle which includes the slot cut-outs shown in Corbin et al. and further including a headlap portion which is darkened with respect to the butt end portion so that when arranged in an overlap fashion the darkened portions simulate bricks.
Thus, the prior art shingles fail to provide butt edge features which are designed to provide a continuous irregular features regardless the roof length to be covered. These prior art devices, although providing a limited irregular butt edge, fail to provide a roof covering whose overall effect is to give the appearance of a genuine slate shingle roofing. In addition, the prior art fails to provide vertical shadow lines which set-off individual simulated shingles from each other and give a more authentic effect without the need for cut-outs.